Editing in academia is a challenge. On the one hand, there is the need for jargon specific to the discipline. On the other, there is a need to make the writing easy to understand and to read. For example, many academics like to use long introductory phrases to explain why they are going to take the action at the end of the sentence. For the reader, this technique is laborious and can lead to rereading the sentence. There is also a tendency to add layers of redundancy; for example, "The firm value is related to firm profits that are the result of firm performance." This is a tough sentence to read. The English language allows this sentence to be simplified: "The firm's value is related to its profits that result from its performance." Now, the sentence is concise and has the same meaning.
Here is a short video on this topic: https://youtu.be/JT0U94349Hc

A lack of parallelism is a problem I see in academic writing all the time. It often happens when authors try to combine two separate thoughts in one sentence. One solution is to create two short sentences, one for each thought. Another is to rework the sentence. In both the trouble for an editor is to pick the correct meaning, which because of the lack of parallelism can be tough.
Here is a brief article from the MLA style guide:
https://style.mla.org/parallelism/ 

Here is a writer's perspective on the need for plain language. She is funny but offers some good advice. E.g., using power point as a way to outline your paper.
www.linkedin.com/feed/update/urn:li:activity:6381189342508961792

Here is the final part of this series as posted on LinkedIn:
https://www.linkedin.com/feed/update/urn:li:activity:6380455115731582976

Here is part two as posted on LinkedIn:
​https://www.linkedin.com/feed/update/urn:li:activity:6368512703102742528

When I edit, I try to simplify the language and smooth some of the jargon. Many academics use jargon to simplify their writing. Common examples are the elimination of articles, noun pairs instead of 's, and catchall words like suggest or impact.
The following link is the first part of two on the reasoning for my editing style:

https://www.chronicle.com/article/PhDs-Are-Still-Writing/241700
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Compound, complex sentences can be opaque. When editing I work to make writing more transparent. Here is my LinkedIn post on this topic:
https://www.linkedin.com/feed/update/urn:li:activity:6330814190026055680

​In my editing, I increasingly see the use of dashes, or the use of hyphens instead, used improperly. There are two kinds of dashes: the en-dash and the em-dash. The following definition for an en-dash comes from The Chicago Guide to Grammar, Usage, and Punctuation by Bryan Garner: An en-dash is a horizontal line that marks a span, a tension, or a pairing of equals. Examples are: good–bad dimension or a London–Paris flight (but do not use it to replace “from-to” phrases: “I flew from London to Paris”.
In academic writing, the en-dash should be used in number sequences: p. 200–201; 1972–1983. In essence, the en-dash translates to “to”: page 200 to page 201. A hyphen is often used instead—I think—because the dash is not on the keyboard.The shortcut for an en-dash on a PC is the following: the “ALT” key plus 0150. Hold the key down while typing the numbers and then release it. The dash will appear. When using this dash there should be no spaces around it unless the journal requires it.
 
The em-dash is more complex. Again, referring to Garner’s book, the definition of an em-dash is as follows: An em-dash is a horizontal line that marks an emphatic insertion, an informal introduction, or a sharp break in thought. Examples are: “In America—as elsewhere—free speech is confined to the dead” (Mark Twain). Here it sets off a phrase modifying America. “They say—the astrologers, I mean—that it will get better and better for me as I go on” (Henry Miller). In this case the dash is being used instead of parentheses to highlight the phrase. The first two examples come from fictional works to add nuance and probably are not appropriate for formal writing. Another use is as a device to hesitation in the sentence.
The most appropriate use in academic writing would be to set off a list in the middle of a sentence: “This market has everything—meat, fish, vegetables, and dairy—that the supermarket has. In this usage, the dash is better than using a colon. However, a sentence should only have two em-dashes at most. Also, they stand alone with no punctuation before or after and, like the en-dash, no spaces. On a PC the shortcut for the em-dash is “ALT” plus 0151. I recommend using the em-dash sparingly in formal writing. It is better suited for fiction.

Here is short clear article on the use of the serial comma, which I support, and the use of a semicolon in lists. In my editing both are very common corrections that I make. https://style.mla.org/2017/06/15/serial-commas-and-semicolons/

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​This tip’s focus is on passive voice. Passive voice is formed with the verb to be and a past participle: is known, was found etc. Passive voice obscures the actor and causes the writer to back into the sentence, e.g., This finding is supported by the authors; as opposed to active voice: The authors support this finding. Or the actor can be left out altogether: This finding was supported.
There are three problems with the passive voice: it adds words; when it doesn’t it hides the actor altogether; and third, it makes it harder for readers to process the information because the logical word order is reversed.
The advantage to the active voice is that it saves words, identifies the actor, and uses the normal actor-verb-object sentence order.
There are times when passive is good. These are usually in the method and result sections of a paper when the actor is obvious and the thing being acted on is the focus, i.e., a result or a method.
Many journals frown on the use of passive voice because it lacks clarity. So, if you want your writing to be clear, stick to active voice as much as possible. And hire a good editor.